Low Resistivity Nickel Germanosilicide Contacts to Ultra-shallow Junctions Formed by the Selective Si_1-x Ge_x Technology for Nanoscale CMOS

Abstract

In this paper, we present our recent results on nickel germanosilicide contacts formed on p⁺-n and n⁺-p junctions formed by selective deposition of in-situ doped Si_1-xGe_x alloys. Our results show that ultra-thin, low resistivity NiSi_1-xGe_x contacts can be formed at temperatures as low as 300°C on both boron and phosphorus doped Si_1-xGe_x layers. Ultra-shallow junctions with excellent reverse leakage behavior and a contact resistivity ∼ of 10^-8 ohm-cm² were successfully demonstrated. The thermal stability of NiSi_1-xGe_x was found to be limited to 500°C on p⁺-Si_1-xGe_x and 600°C onn⁺-Si_1-xGe_x. It was found that by inserting a thin Pt interlayer between Ni and Si_1-xGe_x, the quality of the NiSi_1-xGe_x contacts could be significantly improved. The Pt interlayer was found to improve the interface morphology, which was found to have a direct impact on the electrical properties of the contacts.